Enhancing renal masses with zero net growth during active surveillance

Area of Science:

• Urology
• Oncology
• Radiology

Background:

• Small renal masses (SRMs) typically grow slowly.
• A subset of SRMs exhibits no radiographic growth during observation.
• Active surveillance is a management strategy for SRMs.

Purpose of the Study:

• To compare clinical, radiographic, and pathological characteristics of enhancing renal masses with zero growth versus positive growth under active surveillance.
• To evaluate the natural history of SRMs that do not demonstrate radiographic growth.

Main Methods:

• 106 enhancing renal masses observed for ≥12 months were identified and grouped by growth (zero/negative vs. positive).
• Clinical, radiographic, and pathological parameters were compared between groups.
• A MEDLINE search reviewed literature on zero-growth lesions in suspected renal cell carcinoma.

Main Results:

• 33% of lesions (35/106) showed zero/negative growth (median 0.0 cm/year), while 67% (70/106) showed positive growth (median 0.31 cm/year).
• No significant differences were found in patient age, lesion size, or solid/cystic appearance between groups.
• Malignancy rates were similar (83% vs. 89%), but 51% of growing lesions required intervention versus 17% of non-growing lesions.

Conclusions:

• Definable clinical characteristics to predict growth in enhancing renal masses under surveillance were not identified.
• 26%-33% of SRMs do not demonstrate growth over a median follow-up of 29 months.
• Non-growing SRMs have similar malignancy rates and low metastatic potential, supporting limited treatment for growing lesions only.